What is the difference between weather and Climate?

Weather refers to the more local changes in the climate we see around us, on short timescales from minutes to hours to days to weeks. Examples are familiar – rain, snow, clouds, winds, thunderstorms, heat waves and floods.

Climate refers to longer-term averages (they may be regional or global), and can be thought of as the weather averaged over several seasons, years or decades. Climate change is harder for us to get a sense of because the timescales involved are much longer, and the impact of climate changes can be less immediate. Examples of climate change include several drier-than-normal summers, a trend of, say, winters becoming milder from our grandparents’ childhood to our own, or variations in effects like El Niño or La Niña.

Reference: climate.nasa.cov


What is Global Warming and how does it differ from Climate Change?

Global warming refers to the long-term warming of the planet. Global temperature shows a well-documented rise since the early 20th century and most notably since the late 1970s. Worldwide, since 1880 the average surface temperature has gone up by about 0.8 °C (1.4 °F), relative to the mid-20th-century baseline (of 1951-1980). 


Climate change  encompasses global warming, but refers to the broader range of changes that are happening to our planet. These include rising sea levels, shrinking mountain glaciers, accelerating ice melt in Greenland, Antarctica and the Arctic, and shifts in flower/plant blooming times. These are all consequences of the warming, which is caused mainly by people burning fossil fuels and putting out heat-trapping gases into the air. The terms “global warming” and “climate change” are sometimes used interchangeably, but strictly they refer to slightly different things.


Reference: climate.nasa.gov


Is the sun causing Global Warming?

No. The sun can influence the Earth’s climate, but it isn’t responsible for the warming trend we’ve seen over the past few decades. We know subtle changes in the Earth’s orbit around the sun are responsible for the comings and goings of the ice ages. But the warming we’ve seen over the last few decades is too rapid to be linked to changes in Earth’s orbit, and too large to be caused by solar activity. In fact, recently (2005-2010) the sun has become less active, while temperatures have marched upwards.

One of the “smoking guns” that tells us the sun is not causing global warming comes from looking at the amount of the sun’s energy that hits the top of the atmosphere. Since 1978, scientists have been tracking this using sensors on satellites and what they tell us is that there has been no upward trend in the amount of the sun’s energy reaching Earth. 
Click here for the sun's energy charted against global temperatures.


Reference: climate.nasa.gov

Is it too late to stop climate change?

Human greenhouse gas emissions have caused major climate changes to happen already.  Even if all greenhouse gas emissions stopped today, climate changes would continue to happen for at least several more decades. That’s because it takes a while for the planet to respond, and because carbon dioxide – the predominant heat-trapping gas – lingers in the atmosphere for hundreds of years. There is a time lag between what we do and when we feel it.  But it may not be too late to avoid or limit some of the worst effects of climate change.

Responding to climate change involves a two-tier approach: 1) “mitigation” – reducing the flow of greenhouse gases into the atmosphere; and 2) “adaptation” – learning to live with, and adapt to, the climate change that has already been set in motion.  Because climate change is a truly global, complex problem with economic, social, political and moral ramifications, the solution will require both a globally-coordinated response (such as international policies and agreements between countries, a push to cleaner forms of energy) and local efforts on the city- and regional-level (for example, Climate Action and Adaptation Planning at the City level). It’s up to us what happens next.

Reference: climate.nasa.gov

When Minnesota temperatures can change 30 degrees in a day, how can a change of just a couple degrees be a big deal?

It's important to recognize that weather and climate are related but they are different things. Daily temperature swings of tens of degrees at a given location are common weather-driven events. But when measurements of the daily high and low temperatures in many thousands of locations all over the world—on land and ocean—are examined for an entire year and then averaged together, the Earth's annual average temperatures from year to year are found to be very stable when the climate isn't changing. In a geological context, a 1.5°F (0.85°C) warming over a span of 100 years is an unusually large temperature change in a relatively short span of time and indicates that the climate is changing. This warming is important because it increases the probabilities of extreme weather and climate events.

If global warming were to stop now, its most potentially serious problems would be prevented. However, global warming is expected to continue at an increasing rate. In several decades our world is likely to become warmer than it's been for over a million years, with unpredictable consequences. It's also important to recognize that Earth is not warming uniformly, nor is it expected to. Middle and high latitudes in general change more than the tropics, and land surface temperatures change more than ocean temperatures. Over the long term, land masses at the latitude of the United States are expected to warm much more than the global average.

Reference: NOAA climate.gov

What is a Carbon Footprint?

Simply put, your carbon footprint is the sum total of all the Greenhouse Gas emissions produced by what you do and what you consume.  The place you live, the clothes you wear, the food you eat, that cup of morning coffee, and the car you drive all add to your carbon footprint and overall impact we each have on the environment. 

The term “Carbon Footprint” typically includes all greenhouse gases associated with a product or activity.  Greenhouse gases include carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride, and a wide range of emissions which have weaker but still cumulative effects such as Vollital Organic Compounds (VOC’s). 

Why are greenhouse gases important?

Greenhouse gases are unique atmospheric gases in the way they interact with energy.  They allow light energy traveling from the sun pass directly through them to reach the surface of the earth.  Once that light hits the Earth, it becomes heat energy and a portion of that radiates back out towards space in the form of infrared energy.  Unlike sunlight, infrared energy is absorbed by Greenhouse gases and a portion of that energy is reflected back to the surface of the Earth.  The overall effect Greenhouse gases have is like a layer of insulation keeping a portion of Earth's heat from radiating out into space.

Is climate change responsible for the increase in extreme weather events

An extreme event is a time and place in which weather, climate, or environmental conditions — such as temperature, precipitation, drought, or flooding — rank above a threshold value near the upper or lower ends of the range of historical measurements. Though the threshold is arbitrary, some scientists define extreme events as those that occur in the highest or lowest 5% or 10% of historical measurements.

Human-caused climate change is not the sole cause of any single extreme event. However, changes in the intensity or frequency of extremes may be influenced by human-caused climate change.] Heat waves will tend to be a bit hotter— both the daily high and daily low temperatures. And, because a warmer atmosphere holds more water vapor, precipitation events will tend to be heavier (as measured by total rainfall or snowfall). These are just two examples of how extreme events are becoming more extreme.

Establishing causes of a specific extreme event can be difficult and requires case-specific methods. Scientists can assess whether a specific event (e.g., the 2012 U.S. drought, or the storm surge from Superstorm Sandy) has become more or less likely, or stronger or weaker, as a consequence of human-caused climate change. In nineteen recent analyses of twelve extreme events in 2012, scientists found that some events had direct ties to climate change, while others did not.

What are climate models? How are they used and what can they say

Climate models are mathematical representations of Earth’s climate system, used to get a picture of what the atmosphere and Earth may look like some time in the future in response to natural and anthropogenic processes. (Reference 14)

There is confidence that climate models provide credible quantitative estimates of future climate change, particularly at continental scales and above. This confidence comes from their ability to reproduce observed features of current climate and past climate changes, their success in making predictions that have been subsequently confirmed by observations, and the foundation of the models based on accepted physical principles. (References 15-16)

Despite the science community’s confidence in climate models, models still show significant errors, mainly resulting from the assumptions that all climate models must make about how the Earth works. The complex and non-linear nature of climate means there will always be a process of refinement and improvement. However, models have evolved to the point where they successfully predict long-term trends and are now developing the ability to predict more chaotic, short-term changes. While it is not possible to precisely project all aspects of future climate (in particular because the magnitude of future impacts is based in large part on the outcomes of social and political decisions that are difficult to anticipate), most climate scientists argue there is enough reliable information on future climate trends and patterns to begin implementing robust adaptation strategies (Reference 17)

What local impacts are anticipated in the greater Minneapolis Saint Paul metropolitan region due to climate change

Based on downscaled models for this region, which is a strategy that connects global scale predictions and regional dynamics to generate regionally specific forecasts, the following impacts are expected to occur: (Reference 18)

  • “Migrating seasons” for regional climates: By century’s end, winter is forecasted to feel similar to (edit) and summers similar to (Edit) or, under high emissions, (Edit).
  • Temperature increase: Under high emissions, the Midwest may experience 45-85 days over 95° F by century’s end.
  • Heat-related morbidity: By 2085, there may be (Edit) heat-related Minneapolis Saint Paul metro-area deaths per year.  
  • Changed precipitation patterns: As compared to the 1961-1990 average, spring and winter in 2070 could have 20-35% more.
  • Plant Hardiness Zone shift: The Midwest’s zones have shifted and could continue to shift ½ to 1 zone every 30 years.. 
  • Great Lake impacts: Modeling future lake level projections is extremely complex. The most recent research shows a range of possible conditions, ranging from a slight decrease to a slight increase in Lake Superior during this century (Reference 19). Additionally, the Great Lakes could experience an increased likelihood of extreme storms.

How will these changes affect the nature and wildlife of this region

Climate change may continue to alter many aspects of life in Maplewood. For examples, as the region becomes warmer, drier and experiences more extreme events, the following impacts are likely to occur:
(References 20-22)

  • Animals and plants become stressed from too much heat and too much or too little water;
  • Rivers, lakes and wetlands become more polluted from increased stormwater run–off, which picks up sewage, garbage, fertilizer etc. that then flows into these waterways;
  • Invasive species and pests become more prevalent;
  • Decoupling of important life cycle events occur.

This last example, the decoupling of important life cycle events, such as the timing of migrations and flowering, are likely to occur due to organisms responding differently, and at different rates, to changes in climate. Desynchronization of these relationships will have important consequences for how organisms at different levels of the food web interact with one another. For example, based on observations made by Eric Gyllenhaal in Chicago (Reference 23) in spring 2011, Elm leaf beetles, American Elm trees and Nashville warblers have a tightly synchronized food web interaction in this region. As new leaves appear on the trees in the spring, Elm leaf beetle larvae emerge at the same time to take advantage of this food resource. Migratory warblers typically appear at this time, feeding on the larvae and acting as a natural pest control for the Elms. Spring green-up, however, is already shifting in this region, evidenced by Oak trees now leafing out approximately 2 weeks earlier. As the warm-up continues to advance, and organisms such as trees and insects responding to temperature cues begin to emerge earlier, a mismatch between food availability and that of avian migratory timing could take occur. This would impact the insectivorous migrant birds, and their ability to provide the form of natural pest control for the Elm trees.

How will these changes affect the people who live in Maplewood

People also rely on the many benefits that nature and wildlife provide. These benefits are called ecosystem services, and include things such as providing clean air and water, stormwater abatement, carbon storage, along with cultural and aesthetic values. Additionally, scientists project increases in:

  • Heat–related diseases like heart attacks and asthma;
  • Flooding, affecting residences, public transportation and bridges;
  • Electricity shortages and changes in energy demands;
  • Municipal costs, such as landscaping, road maintenance, and emergency response.

By reducing your own carbon footprint, and by helping our communities, natural areas, and green spaces adapt to the changes that are already occurring—and will continue to occur—we can lessen the severity of these impacts and foster a closer connection between ourselves and the natural systems we are so intrinsically linked to.

What is meant by the terms “climate variability” and “climate change”

Earth’s climate has been changing for billions of years, and it varies on seasonal, annual, decadal, and longer timescales. Due to these natural variations that occur, people who study the climate look at 30 years of weather data at a minimum- and typically much longer- when they want to see the climate pattern for a region.

Climate variability refers to variations in climate on time scales of seasons to decades and is generally controlled by natural ocean and atmospheric processes like the El Niño Southern Oscillation, Arctic Oscillation, and the North Atlantic Oscillation (References 1-3)

Climate variability explains how one winter can be cold and snowy, while the next is milder; or, how one decade is much drier than normal.

Climate change describes long-term (decades or longer) and persistent changes in the climate of a location and occurs because of natural and/or anthropogenic (human) processes. Climatology, the study of climate science, looks at a minimum of 30 years—or 3 decades—of weather pattern data to describe the climate, or change in climate, of a particular region.

Natural processes that can produce a change in Earth’s climate include variations in solar energy received by Earth arising from variable solar activity or slow orbital changes (Reference 4).

Anthropogenic, or human, processes that can produce a change in Earth’s climate include the burning of fossil fuels (which releases greenhouse gases) and land use changes like urbanization, deforestation, and desertification (Reference 5)

Do scientists agree on Climate Change?

Yes, the vast majority of actively publishing climate scientists – 97 percent – agree that humans are causing global warming and climate change. Most of the leading science organizations around the world have issued public statements expressing this, including international and U.S. science academies, the United Nations Intergovernmental Panel on Climate Change and a whole host of reputable scientific bodies around the world.. The number of peer-reviewed scientific papers that reject the consensus on human-caused global warming is a vanishingly small proportion of the published research. The small amount of dissent tends to come from a few vocal scientists who are not experts in the climate field or do not understand the scientific basis of long-term climate processes.

Reference: climate.nasa.gov